This invention relates generally to surface temperature measuring devices. More particularly, the present invention relates to surface temperature measuring devices that are placed in contact with the surface whose temperature is to be measured.
Conventional surface temperature measuring devices have often included a contact plate which is placed in contact with the object surface. The size of such contact plates was determined by a number of factors. On the one hand, the contact plate must not be so small that small, localized deposits on the object surface or the contact plate disproportionately affect the heat flow to the contact surface. Small contact plates are mechanically less robust and easily bend when the temperature measuring device is subjected to a relatively high bearing pressure. On the other hand, if the contact plate is formed to be relatively large, the measurements require more time, as a result of the greater thermal capacity of the plate. It is also a disadvantage of large contact plates that sufficiently large plane areas on the object are often not available. For measuring the surface temperature of cylindrical objects, such as pipes, a separate contact plate or measuring device is required for each diameter of pipe.
Hand-held devices having contact plates are especially unreliable and inaccurate, in part because the contact plate is not placed sufficiently flush on the object surface. Over the time period typically required to measure the temperature, the operator""s hand typically cannot be held still or begins to tremble, as a result of continual body movements. This causes the contact plate to tilt relative to the object surface. Pressing the contact plate more firmly against the surface in an effort to provide better contact generally only serves to increase trembling of the operator""s hand. The trembling movements of the hand are of many different kinds and of large dynamic range, such that they cannot be automatically countered in the signal processing portion of the device.
Briefly stated, the invention in a preferred form is a probe for measuring the surface temperature of a pipe which comprises a detector assembly and a rectangular strap. The detector assembly includes a rigid, unitary clamp member having a bottom, pipe engagement surface, an oppositely disposed upper surface, and first and second locking dogs extending upwardly from the upper surface. The locking dogs define a gap having a width WG. A temperature sensor assembly is carried on the pipe engagement surface. The proximal end portion of the strap is mounted to the clamp member. The strap is flexible, longitudinally resilient and has a thickness TU in an unstretched condition and a thickness TS in a stretched condition, where TU greater than TS, TU greater than WG, and WG greater than TS. The probe is mounted to the pipe for measuring the temperature of the pipe by positioning the pipe engagement surface of the clamp member against the pipe, wrapping the strap around the pipe, and applying a tensile force to the distal end portion of the strap such that the thickness of the strap decreases from TU to TS. The strap is then positioned in the gap between the first and second locking dogs and the tensile force is removed, whereby a segment of the strap disposed between the first and second locking dogs expands to a thickness substantially equal to WG to clamp the strap between the first and second locking dogs.
The clamp member also has oppositely disposed first and second sides and the pipe engagement surface of the clamp member has an arcuate shape, defining a groove extending laterally from the first side of the clamp member to the second side of the clamp member. The temperature sensor assembly includes a resilient member mounted to the clamp member within a recess in the pipe engagement surface. A sensor subassembly mounted to the resilient member extends from the recess and a signal carrying conductor extends from the sensor subassembly and through a port in a one of the sides of the clamp member. A sleeve may be disposed around a portion of the signal carrying conductor proximate to the side of the clamp member, an end portion of the sleeve being mounted to or engaged by the clamp member.
A strap mount extends laterally from the rear surface of the clamp member. The strap mount includes a substantially planar member having first and second identical, longitudinally extending slots forming a bar therebetween. The strap extends from the distal end portion upwardly through the first slot, wraps around the bar and extends downwardly through the second slot to the proximal end portion. The first and second slots each has a width WSL, where WSL greater than TU and WSL less than 2TU, and the proximal end portion of the strap is formed in a loop. The strap is removable from the strap mount by applying a tensile force to the proximal end portion and the looped proximal end portion prevents the strap from being drawn though the strap mount when a tensile force is applied to the distal end portion.
Each of the locking dogs has a triangular-shape and an inner wall, the inner walls defining a V-shaped strap-receiving channel. When the strap is positioned in the gap between the locking dogs, the inner walls of the locking dogs engaging the strap and the V-shape of the strap-receiving channel longitudinally folds the segment of the strap in the strap-receiving channel. Vertically-extending inner corners of the locking dogs form the gap, where 2TU greater than WG greater than 2TS.
It is an object of the invention to provide a new a nd improved probe for measuring the surface temperature of a pipe.
It is also an object of the invention to provide a probe which is temporarily installed by hand to measure the surface temperature of a pipe, but which holds itself in place on the pipe surface.
Other objects and advantages of the invention will become apparent from the drawings and sp specification.